Traditional vehicle climate control strategies utilize engine operation to support continuous or nearly continuous heating, ventilation and air-conditioning (HVAC) operation. With systems that reduce engine operation, such as stop-start enabled powertrains and/or hybrid electric powertrains, engine power is less available to support the climate control system. For example, stop-start enabled powertrains may stop the engine while the vehicle is motionless or at cruising speed. Hybrid electric powertrains may stop the engine under an even broader set of operating scenarios. When the engine is stopped, it may be difficult to employ traditional climate control strategies with the HVAC system operated at full performance continuously to provide optimal interior comfort.
Dage et al. (US 2006/0225450 A1) discloses a hybrid-electric vehicle automatic climate control strategy wherein the engine and air-conditioning (A/C) compressor are stopped if the vehicle is idling or stopped, the A/C compressor is stopped if not needed to maintain user comfort when the vehicle is being driven, and the A/C compressor is stopped in defogging mode if it is no longer needed to eliminate fogging. User comfort is assessed based on user selection of one of four comfort modes, each mode corresponding to a set of HVAC operating setpoints and/or thresholds based largely on temperature and relative humidity sensors. Similarly fogging probability is assessed based on relative humidity measurements.
The inventor herein has recognized a potential issue with the above approach. Namely, that other factors affecting user comfort and HVAC operation, such as open windows, vents, or blower state, can significantly affect the system operation and driver comfort. For example, if the ambient temperature is lower than the vehicle cabin temperature, opening the window or vent to allow ingress of ambient air can be sufficient for cooling the vehicle interior, instead of cycling the engine and/or A/C compressor on and off. Furthermore, there are vehicle operating conditions under which turning the engine and/or A/C compressor off is untenable for maintaining vehicle operating conditions and/or a desired level of comfort for the user. Under such circumstances however, more moderate actions such as lowering engine speed or torque or reducing compressor load can instead be effected in order to provide gains in fuel economy.
One approach that the inventor has taken to at least partially address the aforementioned issues is a method, comprising during a first engine-running condition, where a vehicle window or vent is in a more closed position, operating a climate control system to provide a user requested level of thermal comfort. During a second engine-running condition, where the vehicle window or vent is in a less closed position, the method further comprises limiting the climate control system performance.
In this way, it is possible to take advantage of the vehicle states, such as the window or vent states as set by the vehicle operator, to better control operation of the climate-control system. For example, the climate-control system operation may be limited, for example by reducing compressor or blower speed, thereby conserving energy when possible, without degrading operator comfort.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.